中国清代中后期(1776～1911年)水灾受灾比动态变化及风险评估

^FP VARIATION AND RISK ASSESSMENT DURING THEMIDDLE AND LATTER PERIODS OF QING DYNASTY (1776-1911)IN CHINA

利用中国历史水灾数据，提出用“受灾比”（ＦＰ）表示流域内受灾县域个数占整个流域县域个数的比例。对各大流域ＦＰ时空动态变化及其风险水平的分析结果表明：ＦＰ及相应的风险水平有明显的南北差异，ＦＰ平均月变化和年变化跟降水变化和人类的开垦活动密切相关。

Abstract Based on the historical flood database, FP is put forward as an index to present the proportion of flood impacted counties in a whole drainage basin. Using FP time-series, the flood spatio- temporal variation curves are presented, furthermore, the risk probability is calculated according to the theory of information diffussion. The results reveal the following conclusions: (1) There are obvious spatial variations between the South China and the North China. The maximum FP value locates in Huaihe drainage basin, and it decreases as extending north or south from Huaihe drainage basin. (2)The mensal variation of FP has a close relation to the mensal change of precipitation. The maximum FP Values of South China drainage basins start on June, however, those of North China drainage basins first appear in July. The peak FP value of Huanghe drainage basin persists a long time and that of southeast China has a two - peak character. (3) The increasing FP trend with synchronous liberation, together with the decreasing annual flooded county number, indicates that human activities are expanding to high risk areas and increasing mul